Liquid crystal panel having an organic indium and/or organic zirconium orientation film

ABSTRACT

A liquid crystal panel comprising base plates, at least one of which is a plastic base plate provided with a transparent electrode, and a liquid crystal interposed between the substrates, is provided by forming an orientation controlling film of a composition comprising an organic indium compound and an organic zirconium compound or of a composition comprising an organic indium compound, a polyester resin and an isocyanate resin on the plastic substrate, or is produced by arranging at least two monoaxially stretched films as the substrates so that their stretched directions are in parallel or in counter-directionally parallel with each other.

BACKGROUND OF THE INVENTION

The present invention relates to a liquid crystal panel comprising apair of base plates, at least one of which is a plastic plate, and aliquid crystal material interposed between the base plates.

Most liquid crystal panels practically used heretofore have a structurein which a pair of transparent base plates such as those of inorganicglass or plastic are respectively provided with a transparent electrode,e.g., of tin oxide, indium oxide or a composite of these and subjectedto a homogeneous or horizontal orientation treatment, and a liquidcrystal is disposed between the base plates, whereby a voltage can beapplied between the electrodes. As methods, for the homogeneous orhorizontal orientation treatment, the following methods (a) to (d) havebeen conducted heretofore.

(a) Rubbing of a base plate with, e.g., a cotton cloth in one direction.

(b) Oblique or tilt vapor deposition of SiO or SiO₂.

(c) Rubbing of a film of an organosilane, a linear polyamide, apolyimide, etc., formed on a base plate.

(d) Irradiation of a high energy beam such as electron beam or plasmadischarge.

The above methods are effective for the homogeneous orientationtreatment of inorganic glass plates but have not been fully effectivewith respect to plastic substrates.

Thus, in the method (a), the resultant orientation performance does notlast for a long term and cannot resist aging at 45° C. or above. In themethod (b), the temperature at which the base plate is heated to ensurethe intimate adhesion thereto of deposited SiO or SiO₂ film exceeds theheat deformation temperature of a plastic plate (below about 150° C.)and causes deformation of the base plate. On the contrary, if the vapordeposition is conducted while the base plate is heated to a lowertemperature, the deposited film has a poor adhesion to the plastic baseplate and has a low resistance to aging. In the method (c), anorientation controlling aid such as an organosilane (atrialkoxymonoalkylsiloxane, ordinarily called a silane coupling agent,is generally used and, especially, 3-aminopropyltriethoxysilane isfrequently used) has a poor resistivity to aging. On the other hand,when a polyimide film which is most widely used is intended to beformed, the plastic base plate cannot resist the temperature (250° C. orabove) required for polymerizing a polyamide acid (or a polyamide-imide)which is a precursor of a polyimide. In the method (d), due toirradiation with a high energy beam, the plastic plate or transparentelectrode deteriorates. Moreover, this method is not adapted for massproduction, and an advantage from the viewpoint of production resultingfrom the use of a plastic base plate is lost.

Further, a biaxially stretched polyester film having a thickness of theorder of 100 μm has been used as a plastic film substrate for TN-typeliquid crystal devices in view of various properties such as filmproperties (heat-deformation resistance, chemical resistance,gas-barrier property), appearance (transparency, smoothness), cost,electrical resistance (100-1 kΩ/cm²) and adhesion to the substrate of atransparent electrode (formed, e.g., by vapor deposition orlow-temperature sputtering of indium oxide on a surface-treated film),and little change in performance with the elapse of time. However, abiaxially stretched polyester film has optical anisotropy as shown inFIG. 4. In FIG. 4, reference numeral 21 denotes a biaxially stretchedpolyester film, 22 directions of film stretching, and 23 a direction ofan optical axis (direction of optical rotation). As the biaxiallystretched polyester film has an optical anisotropy as shown in thefigure, it is accompanied with a difficulty in selection and combinationof optical axes of the films and a problem such as occurrence ofinterference color depending on visual field angle. In order to solvethese problems, a monoaxially stretched polyester film has been usedrecently. However, a monoaxially stretched polyester film has a largerheat shrinkage in the MD direction (machine direction) compared with abiaxially stretched polyester film. Therefore, a uniform gap of theorder of 10 μm required for a liquid crystal panel cannot be obtained bymere adjustment of films with respect to the optical axes as has beenconventionally carried out. Further, a large displacement between thepair of electrodes has occurred due to heat shrinkage, wherebydegradation of display qualities has occurred or poor continuity atcontacts with the pair of electrodes has occurred.

Table 1 below shows comparison of heat shrinkages between a biaxiallystretched polyester film and a monoaxially stretched polyester filmafter they were heated for 1 hour in an oven of 150° C.

                  TABLE 1                                                         ______________________________________                                                Film                                                                            Biaxially stretched                                                                         Monoaxially stretched                                 Direction polyester film                                                                              polyester film                                        ______________________________________                                        TD*       -0.23%        0.05%                                                 MD*        0.56%        1.6%                                                  ______________________________________                                         *TD: Transverse direction                                                     MD: Machine direction                                                    

SUMMARY OF THE INVENTION

An object of the present invention is to provide a liquid crystal panelcomprising a pair of base plates at least one of which comprises atransparent plastic base plate on which an orientation controlling filmhaving a high aging resistance or an excellent long term performance hasbeen formed at a temperature below the heat deformation temperature ofthe plastic base plate, without imparing a high productivity resultingfrom the use of a plastic base plate.

Another object of the present invention is to provide a liquid crystalpanel with a high display quality which can be produced continuouslywith an adaptability for mass production resulting from the use of aplastic base plate, while avoiding the drawbacks of the conventionalliquid crystal panels using a plastic base plate.

These and other objects of the present invention can be accomplished bya liquid crystal panel comprising a plastic base plate having atransparent electrode thereon which is provided with an orientationcontrolling film comprising an organic indium compound and an organiczirconium compound or an orientation controlling film comprising anorganic indium compound, a polyester resin and an isocyanate resin.

A further characteristic of the present invention resides in a liquidcrystal panel comprising plastic films as substrates, which comprises asthe plastic films at least two monoaxially stretched films disposed tohave their stretched directions in parallel or in counter-directionallyparallel with each other and a liquid crystal filling the gap betweenthe monoaxially stretched films.

These and other objects, features and advantages of the presentinvention will become more apparent upon a consideration of thefollowing description of the preferred embodiments of the presentinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing an embodiment of the liquid crystalpanel according to the present invention;

FIG. 2 is a sectional view illustrating a base plate with a single layerorientation controlling film; and

FIG. 3 is a sectional view illustrating a base plate with a double layerorientation controlling film;

FIG. 4 is an explanatory view for illustrating an optical anisotropy ofa biaxially stretched polyester film;

FIG. 5 is an explanatory view for illustrating a relationship betweenthe stretched direction and the optical axis of a monoaxially stretchedpolyester film;

FIGS. 6(a), 6(b) and 6(c) and FIGS. 7(a), 7(b) and 7(c) are explanatoryviews illustrating several embodiments of the liquid crystal panelaccording to the present invention;

FIG. 8 is an explanatory view illustrating another embodiment of theliquid crystal panel according to the present invention;

FIG. 9(a) and 9(b) respectively illustrate a comparative example of aliquid crystal display panel;

FIG. 10 is a view for explaining a relationship between the stretcheddirections of a pair of panel base plates.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be explained in detail with reference tothe drawings.

FIG. 1 shows an embodiment of the liquid crystal panel according to thepresent invention. The liquid crystal panel comprises a pair of plasticbase plates 11 each provided with an electrode 12 of a transparentelectroconductive film and an orientation controlling film 13, formedthereon. These base plates are secured to each other with a sealingmember 14, a conductive member 15 conducting the electrodes 12 of thebase plates and gap-forming members 16 disposed therebetween. A liquidcrystal 17 is sealed in a space formed between or interposed between thebase plates 11 with their faces having the orientation controlling films13 facing each other.

The plastic base plate 11 is formed from a plastic such as polyethyleneterephthalate, polybutylene terephthalate, polyethersulfone,polycarbonate, cellulose triacetate or polyol. On the base plate 11 isformed a transparent electroconductive film 12 of tin oxide, indiumoxide, etc., by a known technique such as vacuum evaporation,low-temperature sputtering, or CVD (chemical vapor deposition).

In the present invention, the plastic base plate 11 having such atransparent electrode 12 is further provided with an orientationcontrolling film 13 comprising an organic indium compound and an organiczirconium compound.

The organic indium compound used in the present invention is preferablyone represented by the general formula In(OR)₃, wherein R is an alkylgroup. Specific examples thereof include In(OC₂ H₅)₃, In(OC₃ H₇)₃ andIn(OC₅ H₁₁)₃. An organic indium compound having R=--C₃ H₇ in the abovegeneral formula is especially preferred in view of production andhandling thereof.

The organic zirconium compound include those of the alkoxy type such astetraisopropoxyzirconium (Zr(i-OC₃ H₇)₄) and the chelate type such aszirconium acetylacetonate (Zr(CH₃ COCHCOCH₃)₄). From the viewpoints ofstability of reaction with the above mentioned organic indium compound,orientation performance for liquid crystals, film formationcharacteristic and handling, the latter chelate type is especiallypreferred.

The orientation controlling film 13 may be formed in a single layer orin two layers. The proportions between the organic metal compounds inthe orientation controlling film vary depending on the structure of thefilm, i.e., whether the film comprises a single layer or two layers.

Structure 1: A single layer of mixture of an organic indium compound andan organic zirconium compound.

A single layer of the mixture as shown in FIG. 2 preferably comprises100 to 1000 parts by weight, particularly 500 to 1000 parts by weight,of the organic zirconium compound with respect to 1 part by weight ofthe organic indium compound (calculated as In₂ O₃ based on the amount ofIn contained therein) in view of the film forming characteristic andorientation performance. More specifically, when an alkoxy type of theorganic indium compound and a chelate type of the organic zirconiumcompound are used, too small an amount of the organic indium compoundresults in an inferior durability of the orientation performance and alarger amount of the organic indium compound generally increases thedurability of the orientation performance. However, when the organicindium compound is used in an amount exceeding the upper limit, theorientation performance per se is impaired or lost.

Structure 2: A double layer structure with a first layer of a mixturecomprising the organic indium compound and the organic zirconiumcompound and a second layer of either the organic zirconium compound ororganic indium compound.

A structure as shown in FIG. 3 comprising a first layer 18 containingboth of the organic metal compounds and a second layer 19 formed thereoncomprising either one of the organic compounds facilitates theimprovement in film formability and durability of the orientationperformance compared with the above structure 1.

The first layer should preferably comprise 10 to 100 parts, particularly20 to 50 parts, by weight of the organic zirconium compound with respectto 1 part by weight of the organic indium compound (calculated as In₂O₃).

The second layer contains only one kind of the organic metal compoundsand therefore has no compositional limitation. However, when the secondlayer is formed by coating and drying a solution of an organic metalcompound, it is preferred that the solution contains 1-5 wt. % of theorganic metal compound. This is because too low a concentration resultsin an insufficient orientation performance whereas too high aconcentration results in such difficulties as waving of the resultantfilm, occurrence of interference color in reflected light due torefractive index and increase in resistance above the transparentelectroconductive film.

The solvent to be used for dissolving the organic metal compounds isselected through consideration of storage stability of the solution,vaporizability required for formation of the orientation controllingfilm, remaining in the film, effect on the substrate, etc., in additionto solubility of the organic metal compound therein. Specific examplesof the solvent are explained in the working examples describedhereinafter.

A solution containing the above ingredient satisfying the aboverequirement is coated on a substrate and dried at 60° to 150° C. to forman orientation controlling film. The orientation controlling film shouldpreferably have a thickness of 100 Å or less, particularly 20-50 Å orhave a dry coating amount of 0.005-0.05 g/m². If the two layer structureis desired, the second layer is formed in a similar manner after thefirst layer is formed. In this case, each layer should preferably have athickness or dry coating amount as described above.

The film thus formed is then rubbed with a cotton cloth, etc., under astatic pressure of 20 to 200 g/cm², preferably around 100 g/cm² to givean orientation controlling film. A liquid crystal is charged to fill agap between a pair of base plates, at least one of which is a plasticbase plate with an orientation controlling film prepared as above,whereby a liquid crystal panel according to the present invention isobtained.

The orientation controlling film as explained above for giving theliquid crystal panel according to the present invention can be easilyformed by a method such as dipping, spraying and spinner coating,without requiring a vacuum step, a patterning step (etching fordevelopment, peeling) or a printing step. Accordingly, the orientationcontrolling film is adapted to continuous mass production. Thus, aliquid crystal display panel using a plastic film substrate can beeasily manufactured because the orientation controlling film can bestably formed without requiring a high temperature for the filmformation.

In the present invention, the orientation controlling film 13 as shownin FIG. 2 can also be a film comprising an organic indium compound, apolyester resin and an isocyanate resin.

The organic indium compound (referred to as "component A") is selectedfrom those explained above, i.e., is preferably one represented by thegeneral formula In(OR)₃, wherein R is an alkyl group. Specific examplesthereof include In(OC₂ H₅)₃, In(OC₃ H₇)₃ and In(OC₅ H₁₁)₃. An organicindium compound having R=--C₃ H₇ in the above general formula isespecially preferred in view of production and handling thereof.

The polyester resin (referred to as "compound B") is preferably a linearsaturated polyester. Specific examples of the polyester resin includesaturated polyesters or copolymers thereof obtained by reaction of oneor more of saturated polycarboxylic acids such as terephthalic acid,isophthalic acid, adipic acid, sebacic acid, and trimellitic anhydride,one or more of saturated polyols such as ethylene glycol, propyleneglycol, and neopentyl glycol; and optionally a vinyl monomer such asstyrene, methyl methacrylate, and diallyl phthalate in the presence ofvarious initiators or promoters. A copolymer polyester, i.e., apolyester comprising two or more carboxylic acids and a polyol or apolyester comprising a carboxylic acid and two or more polyols, ispreferred. A polyester comprising terephthalic acid as a principal acidconstituent and having a melting point Tm satisfying 60° C.<Tm<150° C.is especially preferred in view of convenience in formation of theorientation controlling film, heat resistance and reactivity.

The isocyanate resin (referred to as "component C") includes anisocyanate group (--NCO)-containing compound alone or a mixture thereofwith a substance having a group such as a hydroxyl group (--OH), aminogroup (--NH₂) or carboxyl group (--COOH) reactive with the isocyanategroup and is characterized by a high polarity and reactivity due to theisocyanate group. Examples of the isocyanate resin includetriphenylmethane-triisocyante (Trade name: Desmodur R),tris(4-phenylisocyanate)thiophosphate (Trade name: Desmodur RF), TDI(tolylene diisocyanate) dimer (Trade name: Desmodur TT), TDI trimer(Trade name: Desmodur IL), 2,4,4'-diphenylethertriisocyanate (Tradename: Hylen DM), HDI (methylene di-para-phenylene isocyanate) (Tradename: Coronate AP), and a polyisocyanate such as a reaction product ofTDI and trimethylolpropane (Trade name: Coronate L). These isocyanatecompounds are considered to react with the polyester to improve the filmproperty of the orientation controlling film. A polyisocyanate isespecially preferred in view of toxicity, easiness of handling, storagestability, and reactivity for formation of the orientation controllingfilm.

The orientation controlling film should preferably contain thecomponents A, B and C in weight proportions of A/B/C=5-20/20-100/1-10 (Abeing calculated as In₂ O₃), more preferably A/B/C=10/30-60/2-5, andmost preferably A/B/C in weight proportions around 10/40/3 in view ofstability of the orientation performance.

The components A, B and C are applied on the substrate in the form of asolution. Preferred examples of the solvent to be used for the purposeinclude those of a ketone type such as acetone, methyl ethyl ketone anddimethyl ketone, and those of a cyclic ether type such astetrahydrofuran and dioxane. A particular solvent to be used is selectedin consideration of such factors as dissolving power for the respectivecomponents, non-reactability with the components, evaporation during theformation of the orientation controlling film and remaining in the film.

The components A, B and C should preferably be used in a proportion of0.1 to 5% by weight in total and particularly 1% by weight or less, inview of orientation performance and formation of a uniform film.

A solution containing the components for forming the orientationcontrolling film satisfying the above conditions is applied on asubstrate and dried at a temperature of from 60° C. to 150° C. to form afilm with a thickness of preferably 100 Å or less, particularlypreferably 20-50 Å. The film is then rubbed with a cotton cloth, etc.,under a static pressure of 20 to 200 g/cm², preferably around 100 g/cm²to give an orientation controlling film. A liquid crystal is filledbetween a pair of base plates, at least one of which is a plastic baseplate with an orientation controlling film prepared as above, whereby aliquid crystal panel according to the present invention is obtained.

The orientation controlling film as explained above for giving theliquid crystal panel according to the present invention can be easilyformed by a method such as dipping, spraying and spinner coating withoutrequiring a vacuum step, a patterning step (etching for development,peeling) or a printing step. Accordingly, the orientation controllingfilm is adapted to continuous mass production. Thus, a liquid crystaldisplay panel using a plastic film substrate can be easily manufacturedbecause the orientation controlling film can be stably formed withoutrequiring a high temperature for the film formation.

FIG. 5 illustrates a relationship between the stretching direction 32and the optical axis direction 33 of a monoaxially stretched polyesterfilm 31. When FIG. 5 is compared with FIG. 4 illustrating a biaxiallystretched polyester film, the monoaxial stretching gives a film having asimple and uniform relationship between the stretching direction andoptical axis. Accordingly, a substrate for a liquid crystal panel can beeasily cut out uniformly and continuously from the film, thus a highproductivity is attained.

FIGS. 6, 7 and 8 show various examples of combined arrangements of 2 or3 substrates formed from a monoaxially stretched polyester film. Liquidcrystal panels are obtained by filling liquid crystals between thesubstrates. In the figures, reference numeral 1A denotes an upper panelsubstrate, 1B a lower panel substrate, and 1C an intermediate substrate.Reference numerals 2A, 2B and 2C denote stretched directions of upper,lower and intermediate panel substrates, respectively. The liquidcrystals filled between the panel substrates are not shown in thefigures.

FIGS. 6(a), 6(b) and 6(c) illustrate the arrangement of upper and lowerpanel substrates with their stretched directions being in(co-directionally) parallel with each other in an oblique direction, theMD direction and the TD direction, respectively. FIGS. 7(a), 7(b) and7(c) illustrate the arrangement of upper and lower panel substrates withtheir stretched directions being in counter-directionally parallel witheach other in an oblique direction, the MD direction and the TDdirection. FIG. 8 illustrates the arrangement of the three panelsubstrates with their stretching directions being in parallel with eachother in an oblique direction.

According to the above described relationships or arrangement betweenthe substrates, conventional difficulties accompanying the use ofmonoaxially stretched films such as warping or distortion of panel oroccurrence of irregular gap due to heat shrinkage are prevented.

FIGS. 9(a) and 9(b) respectively show comparative examples, in each ofwhich upper and lower substrates are so arranged that their stretcheddirections cross each other to form right angles. In these cases, whenthese films are secured to each other under heating (at 80° C. to 150°C.), the resulting panel is noticeably warped or distorted, and a gapbetween the substrate also becomes irregular.

The degree of parallelism between the stretched directions of the upperand lower substrates depends on the temperature at which they areheated. Generally, the angle θ (see FIG. 10) between the stretcheddirection 2A of the upper substrate and the stretched direction 2B ofthe lower substrate should desirably be 10° or less, particularly 5° orless.

As described hereinabove, according to the present invention monoaxiallystretched films are used as liquid crystal panel substrates and theirstretched directions are held in co-directionally parallel orcounter-directionally parallel with each other, whereby severaldifficulties accompanying the use of monoaxially stretched films assubstrates for a liquid crystal panel such as warping or distortion ofthe panel and irregularity of gap due to heat shrinkage are obviated.Further, even if an electrode pattern is deformed due to heat shrinkage,the deformation occurs in common with upper and lower substrates,whereby undesirable displacement of electrode patterns between thesubstrates hardly occur. Accordingly, the degradation of display qualityor conduction errors between the upper and lower electrodes isprevented. Moreover, an electrode pattern after heat treatment can beaccurately determined by designing the pattern while taking the rate ofshrinkage into considertion in advance. Thus, a liquid crystal panelusing a plastic film substrate can be continuously produced withoutimpairing its advantage of adaptability to mass production.

Liquid crystals to be uesd in the present invention include TN (twistednematic)-type liquid crystals, for example.

The present invention will be further described in detail with referenceto examples. It should be understood that the present invention is notlimited to the following examples.

EXAMPLE 1

There was provided a plastic film substrate comprising polyethyleneterephthalate film of 100 μm in thickness on which a transparentelectroconductive film consisting mainly of indium oxide had been formedby using a low-temperature sputtering apparatus while maintaining thefilm temperature below 120° C. On the electroconductive film of theplastic film substrate, a solution of the following composition wasapplied at a rate of 1 g/m² by spinner coating (1000 rpm) and dried at120° C. for 30 minutes to form a film.

    ______________________________________                                            Zr(CH.sub.3 COCHCOCH.sub.3).sub.4                                                              1      g                                                     In(OC.sub.3 H.sub.7).sub.3 *.sup.1                                                             2.5    mg (calculated as In.sub.2 O.sub.3)                   EtOH             100    ml                                                ______________________________________                                        *.sup.1 Because of hydrolyzability in air, In(Oc.sub.2 O.sub.3 was            supplied as a                                                                 2.5% (1.25 wt. % calculated as In.sub.2 O.sub.3) solution in the              following                                                                     solvent system.                                                               Solvent system:      n-buthanol   16%                                                              isopropyl alcohol                                                                          20%                                                              acetylacetone                                                                               2%                                                              propionic acid                                                                             24%                                                              ethyl alcohol                                                                              32%                                                              turpentine oil                                                                              6%                                     

The coating film was then rubbed in one direction with a cotton clothunder a pressure of 100 g/cm². A pair of the thus obtained substrateswere stacked on each other with their rubbing directions crossing eachother with right angles. A pyrimidine-type nematic liquid crystal (Δε>0,Loche RO-TN-619) was filled in a gap between the substrates to form aliquid crystal panel.

COMPARATIVE EXAMPLE 1

A liquid crystal panel was prepared in the same manner as in Example 1except that a solution not containing In(OC₃ H₇)₃ was used.

COMPARATIVE EXAMPLE 2

A liquid crystal panel was prepared in the same manner as in Example 1except that a solution not containing Zr(CH₃ COCHCOCH₃)₄ was used.

EXAMPLE 2

On the plastic substrate of Example 1, the following solution A wasapplied at a rate of 1 g/m² and dried at 120° C. for 20 minutes, and thefollowing solution B was applied at a rate of 1 g/m² and dried at 120°C. for 20 minutes.

A liquid crystal panel was prepared by repeating the rubbing andsubsequent steps of Example 1 while using a pair of the abovesubstrates.

    ______________________________________                                        Solution A:                                                                          In(OC.sub.3 H.sub.7).sub.3 *.sup.1                                                              50      mg                                                              (as In.sub.2 O.sub.3)                                             Zr(CH.sub.3 COCHCOCH.sub.3).sub.4                                                               1       g                                                   Et OH             100     ml                                           Solution B:                                                                          Zr(CH.sub.3 COCHCOCH.sub.3).sub.4                                                               2       g                                                   Et OH             100     ml.                                          ______________________________________                                         *.sup.1 The same form as in Example 1.                                   

The liquid crystal panels prepared in the above Examples and ComparativeExamples were subjected to a durability test. The results are shown inTable 2 below.

                  TABLE 2                                                         ______________________________________                                        Orientation performance after the durability test                                       Test Conditions                                                                 Initial 80° C.,                                                                          80° C.,                                                                      80° C.,                            panel       stage   10 min.   60 min.                                                                             480 min.                                  ______________________________________                                        Example 1   O       O         O     O                                         Example 2   O       O         O     O                                         Comparative O       Δ   X     --                                        Example 1                                                                     Comparative X       --        --    --                                        Example 2                                                                     ______________________________________                                         O: Uniform orientation                                                        Δ: Partially poor orientation (Defects such as domains and rubbing      streaks appeared)                                                             X: Homogeneous orientation not attained or 50% or less of oriented region                                                                              

Orientation performance was evaluated by placing a liquid crystal panelbetween a pair of polarizers with their polarizing directions crossingeach other with right angles, and by observing a light passing throughthe panel from the normal direction with respect to the panel frace.

EXAMPLE 3

On the same plastic film substrate with the electroconductive film as inExample 1, a solution of the following composition was applied and driedat 120° C. for 30 minutes.

    ______________________________________                                        Tetrahydrofuran/methyl ethyl ketone                                                                  10     ml/90 ml                                        In(OC.sub.3 H.sub.7).sub.3 *.sup.1                                                                   31.25  mg                                                                     (as In.sub.2 O.sub.3)                                      Saturated copolymer polyester*.sup.2                                                                 62.5   mg                                              Polyisocyanate*.sup.3  4.7    mg                                          ______________________________________                                         *.sup.1 The same form as in Example 1                                         *.sup.2 Vilon 30P, available from Toyobo K.K. A crystalline saturated         copolymer polyester comprising terephthalic acid as a principal acid          component. M.W. = 18000-20000, Tg = -28° C., Melt Viscosity: 2000      cps (200° C.), m.p. = 125° C.                                   *.sup.3 Coronate L. A 75% solution of a reaction product of 3 mols of         tolylene diisocyanate (TD1) and 1 mol of trimethylolpropane in ethyl          acetate.                                                                 

The coating film was then rubbed in one direction with a cotton clothunder a pressure of 100 g/cm². A pair of the thus obtained substrateswere stacked on each other with their rubbing directions crossing eachother with right angles. A pyrimidine-type nematic liquid crystal (Δε>0,Loche RO-TN-619) was filled in a gap between the base plates to form aliquid crystal panel.

EXAMPLE 4

A liquid crystal panel was prepared in the same manner as in Example 3except that the crystalline saturated copolymer polyester consistingprincipally of terephthalic acid was replaced by an amorphous saturatedcopolymer polyester (Vilon 300 available from Toyobo, K.K., Molecularweight: 20000-25000, Tg=7° C., Melt viscosity=800 cps (200° C.),Softening point=123° C.).

EXAMPLE 5

A liquid crystal panel was prepared in the same manner as in Example 3except that the polyisocyanate was replaced by triphenylmethanetriisocyanate (Trade name: Desmodur R).

COMPARATIVE EXAMPLE 3

A liquid crystal panel was prepared in the same manner as in Example 3except that a solution of a composition not containing the organicindium compound was used.

COMPARATIVE EXAMPLE 4

A liquid crystal panel was prepared in the same manner as in Example 3except that a solution not containing the organic indium compound northe isocyanate resin was used.

COMPARATIVE EXAMPLE 5

A liquid crystal panel was prepared in the same manner as in Example 3except that a solution not containing the unsaturated polyester nor theisocyanate resin was used.

The liquid crystal panels prepared in Examples 3-5 and ComparativeExamples 3-5 were subjected to the durability test.

The results are summarized in Table 3 below.

                  TABLE 3                                                         ______________________________________                                        Orientation performance after the durability test                                       Test conditions                                                                 Initial 80° C.,                                                                          80° C.,                                                                      80° C.,                            Panel       stage   10 min.   60 min.                                                                             480 min                                   ______________________________________                                        Example 3   O       O         O     O                                         4           O       O         O     Δ                                   5           O       O         O     O                                         Comparative O       O         Δ                                                                             Δ                                   Example 3                                                                     4           O       Δ   X     --                                        5           X       --        --    --                                        ______________________________________                                    

The methods and standards of evaluation of the orientation performanceare the same as those explained with reference to Table 2.

What is claimed is:
 1. A liquid crystal panel, comprising a pair of baseplates, at least one of which is a plastic base plate, and a liquidcrystal disposed between the pair of base plates, said plastic baseplate being provided with an orientation controlling film formed byapplying thereon a composition comprising an organic indium compound andan organic zirconium compound.
 2. The liquid crystal panel according toclaim 1, wherein said organic indium compound is a compound representedby the general formula

    In(OR).sub.3,

wherein R is an alkyl group.
 3. The liquid crystal panel according toclaim 2, wherein said R is --C₃ H₇.
 4. The liquid crystal panelaccording to claim 1, wherein said organic zirconium compound has analkoxy group.
 5. The liquid crystal panel according to claim 4, whereinsaid alkoxy group is an isopropoxy group.
 6. The liquid crystal panelaccording to claim 1, wherein said organic zirconium compound is azirconium acetylacetonate chelate compound.
 7. The liquid crystal panelaccording to claim 1, wherein said plastic base plate is formed from amember selected from the group consisting of polyethylene terephthalate,polybutylene terephthalate, polyethersulfone, polycarbonate, cellulosetriacetate, and polyol.
 8. The liquid crystal panel according to claim1, wherein said composition constituting said orientation controllingfilm comprises 1 part by weight of said organic indium compound and 100to 1000 parts by weight of said organic zirconium compound.
 9. Theliquid crystal panel according to claim 1, wherein said compositionconstituting said orientation controlling film comprises 1 part byweight of said organic indium compound and 500 to 1000 parts by weightof said organic zirconium compound.
 10. A liquid crystal panel,comprising a pair of base plates, at least one of which is a plasticbase plate, and a liquid crystal disposed between the pair of baseplates, said plastic base plate being provided with an orientationcontrolling film comprising a first film formed by applying thereon acomposition comprising an organic indium compound and an organiczirconium compound, and a second film formed by applying thereon asecond composition comprising an organic indium compound or an organiczirconium compound.
 11. The liquid crystal panel according to claim 10,wherein said composition constituting said first film comprises 1 partby weight of said organic indium compound and 10 to 100 parts by weightof said organic zirconium compound.
 12. The liquid crystal panelaccording to claim 10, wherein said composition constituting said firstfilm comprises 1 part by weight of said organic indium compound and 20to 50 parts by weight of said organic zirconium compound.
 13. The liquidcrystal panel according to claim 10, wherein said organic indiumcompound constituting said first or second film is a compoundrepresented by the general formula

    In(OR).sub.3,

wherein R is an alkyl group.
 14. The liquid crystal panel according toclaim 13, wherein said R is --C₃ H₇.
 15. The liquid crystal panelaccording to claim 10, wherein said organic zirconium compoundconstituting said first or second film has an alkoxy group.
 16. Theliquid crystal panel according to claim 15, wherein said alkoxy group isan isopropoxy group.
 17. The liquid crystal panel according to claim 10,wherein said organic zirconium compound constituting said first orsecond film is a zirconium acetylacetonate chelate compound.
 18. Aliquid crystal panel, comprising a pair of base plates, at least one ofwhich is a plastic base plate, and a liquid crystal disposed between thepair of base plates, said plastic base plate being provided with anorientation controlling film formed by applying thereon a compositioncomprising an organic indium compound, a polyester resin and anisocyanate resin.
 19. The liquid crystal panel according to claim 18,wherein said organic indium compound is a compound represented by thegeneral formula

    In(OR).sub.3,

wherein R is an alkyl group.
 20. The liquid crystal panel according toclaim 19, wherein said R is --C₃ H₇.
 21. The liquid crystal panelaccording to claim 18, wherein said composition constituting saidorientation controlling film comprises said organic indium compound (A),polyester resin (B) and isocyanate resin (C) in the weight proportionsof A/B/C=5-20/20-100/1-10 with proviso that the amount A is calculatedin terms of the corresponding weight of In₂ O₃.
 22. The liquid crystalpanel according to claim 18, wherein said polyester resin is a linearsaturated polyester.
 23. The liquid crystal panel according to claim 22,wherein said saturated polyester is a copolymer polyester.
 24. Theliquid crystal panel according to claim 18, wherein said plastic baseplate is formed from a member selected from the group consisting ofpolyethylene terephthalate, polybutylene terephthalate,polyethersulfone, polycarbonate, cellulose triacetate and polyol.